A scale-invariant model for snow slab avalanches

Chiaia, Bernardino; Frigo, Barbara

doi:10.1088/1742-5468/2009/02/p02056

Cited by 8 publications

(10 citation statements)

References 44 publications

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“…While qualitatively their results showed similar trends for the evolution of the knock-down function with CV, quantitatively the results were very different. Chiaia and Frigo [2009] also used a related approach based on a scale-invariant fractal model to evaluate the conditions of failure of a slab-WL system taking into account a random distribution of the shear strength. They showed, in particular, how complex local interactions and failures at small scales may lead to catastrophic failure at the macroscopic scale.…”

Section: Discussionmentioning

confidence: 99%

“…Hence, to investigate slope stability and avalanche release size, measured variations in snow properties have been used as input for numerical models of slab-weak layer systems [Failletaz et al, 2004;Zaiser, 2004, 2007;Chiaia and Frigo, 2009;Gaume et al, 2012Gaume et al, , 2013a. By coupling results of a mechanical model accounting for variations in the mechanical properties of the weak layer with observed snowfall GAUME ET AL.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of slope stability with respect to snowpack spatial variability

Gaume¹,

Schweizer²,

Herwijnen³

et al. 2014

JGR Earth Surface

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The evaluation of avalanche release conditions constitutes a great challenge for risk assessment in mountainous areas. The spatial variability of snowpack properties has an important impact on snow slope stability and thus on avalanche formation, since it strongly influences failure initiation and crack propagation in weak snow layers. Hence, the determination of the link between these spatial variations and slope stability is very important, in particular, for avalanche public forecasting. In this study, a statistical-mechanical model of the slab-weak layer (WL) system relying on stochastic finite element simulations is used to investigate snowpack stability and avalanche release probability for spontaneously releasing avalanches. This model accounts, in particular, for the spatial variations of WL shear strength and stress redistribution by elasticity of the slab. We show how avalanche release probability can be computed from release depth distributions, which allows us to study the influence of WL spatial variations and slab properties on slope stability. The importance of smoothing effects by slab elasticity is verified and the crucial impact of spatial variation characteristics on the so-called knock-down effect on slope stability is revisited using this model. Finally, critical length values are computed from the simulations as a function of the various model parameters and are compared to field data obtained with propagation saw tests.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Evaluation of slope stability with respect to snowpack spatial variability

Gaume¹,

Schweizer²,

Herwijnen³

et al. 2014

JGR Earth Surface

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“…Therefore, we argue that snow density is a function of the scale and the probability to find large defects (e.g. superweak zones in a weak layer) increases with the dimension of the snow grain, as for example providing more intrinsic brittleness for large snow slopes [32,33]. Numerical results reported…”

Section: Menger Sponge Modelmentioning

confidence: 78%

Snow metamorphism: A fractal approach

et al. 2010

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Snow is a porous disordered medium consisting of air and three water phases: ice, vapor, and liquid. The ice phase consists of an assemblage of grains, ice matrix, initially arranged over a random load bearing skeleton. The quantitative relationship between density and morphological characteristics of different snow microstructures is still an open issue. In this work, a three-dimensional fractal description of density corresponding to different snow microstructure is put forward. First, snow density is simulated in terms of a generalized Menger sponge model. Then, a fully three-dimensional compact stochastic fractal model is adopted. The latter approach yields a quantitative map of the randomness of the snow texture, which is described as a three-dimensional fractional Brownian field with the Hurst exponent H varying as continuous parameters. The Hurst exponent is found to be strongly dependent on snow morphology and density. The approach might be applied to all those cases where the morphological evolution of snow cover or ice sheets should be conveniently described at a quantitative level.

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“…Various mechanical models that have been used to address the dry snow slab avalanche release problem focused on weak layer failure: e.g. crack models inspired by the over-consolidated clay theory (McClung, 1979), cellularautomata models (Fyffe and Zaiser, 2004), fibre-bundle model (Reiweger et al, 2009), physical-statistical models (Chiaia and Frigo, 2009), multiple finite element method, FEM (Stoffel, 2005;Podolskiy et al, 2013), and analytical and empirical models (Zeidler and Jamieson, 2006). Recent studies, based on FEM with interfacial constitutive laws for weak layers, have shown that one of the key uncertainties in avalanche forecasting, spatial heterogeneity of weak layers, can be treated by statistical methods and that its importance is reduced for greater snow slab depths (Gaume, 2012;Gaume et al, 2012Gaume et al, , 2013.…”

Section: Introductionmentioning

confidence: 99%

Evaluating snow weak-layer failure parameters through inverse finite element modelling of shaking-platform experiments

Podolskiy¹,

Chambon²,

Naaïm³

et al. 2015

Nat. Hazards Earth Syst. Sci.

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Abstract. Snowpack weak layers may fail due to excess stresses of various natures, caused by snowfall, skiers, explosions or strong ground motion due to earthquakes, and lead to snow avalanches. This research presents a numerical model describing the failure of "sandwich" snow samples subjected to shaking. The finite element model treats weak layers as interfaces with variable mechanical parameters. This approach is validated by reproducing cyclic loading snow fracture experiments. The model evaluation revealed that the Mohr-Coulomb failure criterion, governed by cohesion and friction angle, was adequate to describe the experiments. The model showed the complex, non-homogeneous stress evolution within the snow samples and especially the importance of tension on fracture initiation at the edges of the weak layer, caused by dynamic stresses due to shaking. Accordingly, a simplified analytical solution, ignoring the inhomogeneity of tangential and normal stresses along the failure plane, may incorrectly estimate the shear strength of the weak layers. The values for "best fit" cohesion and friction angle were ≈ 1.6 kPa and 22.5-60 • . These may constitute valuable first approximations in mechanical models used for avalanche forecasting.

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A scale-invariant model for snow slab avalanches

Cited by 8 publications

References 44 publications

Evaluation of slope stability with respect to snowpack spatial variability

Evaluation of slope stability with respect to snowpack spatial variability

Snow metamorphism: A fractal approach

Evaluating snow weak-layer failure parameters through inverse finite element modelling of shaking-platform experiments

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